Veðrið er kalt, en við göngum samt í skóginn.

to be

Breakdown of Veðrið er kalt, en við göngum samt í skóginn.

• við: we
• veðrið: the weather
• kaldur: cold

Questions & Answers about Veðrið er kalt, en við göngum samt í skóginn.

Why is it Veðrið and not just veður?

Veður means weather (indefinite). Veðrið is the weather (definite). Icelandic often uses the definite form for general statements about “the weather” in the situation you’re talking about (like “the weather (today/right now)”).
Form: veður + definite suffix -ið → veðrið (neuter singular).

What’s going on with the word veðrið—why does ð appear and how is it pronounced?

The base noun is veður. When you add the definite ending -ið, it becomes veðrið. The ð is part of the stem and stays.
Pronunciation note: ð is often like the th in this, but in many positions it can be very soft or even barely pronounced depending on the surrounding sounds and speaking style.

Why is the sentence Veðrið er kalt and not Veðrið er kaldur/köld?

Because veður/veðrið is neuter singular, the adjective must agree:

• masculine: kaldur
• feminine: köld
• neuter: kalt ✅
  So kalt matches veðrið in gender (neuter), number (singular), and case (nominative here).